Can I use cedar for railing posts

by John
(Texas)

I would like to know if I can use cedar for railing posts on my deck?

The deck framing is 2x8 treated floor joists. I've been told that cedar it is too soft and I should use 4x4 treated pine and skin it with cedar.

What are the facts?

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Editor's Comments

Like most things in life nothing is truly black and white. Much of life is gray. So you have to dig into the details to get to the truth.

Here goes:

You have raised a great question that cuts to the core of the differences of the qualities of the dimensional lumber made from various species of wood used in outdoor structures like a deck.

Not All Softwoods Are Alike

The most common species used for outdoor structures like a deck are cedar, redwood and a variety of species that are pressure treated in order to preserve them and extend their life span.

Species used for pressure treating are southern yellow pine, eastern white pine, hem-fir, spruce and there may be others.

The softer species are the western red cedar and redwood species. Spruce actually has a lower density that western red cedar according to a number of publicly available wood density charts.

Yellow pine is one of the hardest of the softwoods. Douglas fir is also a softwood but is really hard. In fact it harder than some maple. But it is a "softwood".

Cedar For Railing Posts

If you set the posts into the joists and block them and use various bolts, and joist connectors there is no reason that a cedar post can not perform and exceed the minimmum standards set out in residential codes.

Here is a great series of illustrations and detailed explanation of how to attach wood posts securely into a joist framed structure for all softwoods.

Read this article.

A Couple Final Notes

For the benefit of some visitors from other jurisdictions like Canada and specifically Ontario, there is a section of the residential code called SB7 Guidelines.

There are a series of axiomatic drawings of explicit ways that railings for decks can be built and will be considered acceptable to a local inspector.

Alternate Methods

And there are also alternative ways to connect posts or manufactured railing systems which are permitted so long as the manufacturer can provide independent engineering test results which are performed in accordance with the sanctioned test procedures such as:

ASTM 7032 D for IRC (US)

Canadian, UK and Australian codes call for slightly different testing procedures but the end result is the same - testing results showing that a railing built according to the manufacturers directions will meet the minimum code performance standards.

So, yes you can use cedar for railing posts subject to above discussion and details.